1. Field of the Invention
The present invention relates to an infrared ray detection device suitable to detect an infrared ray of a long wavelength from several microns up to about 20 microns.
2. Description of the Related Art
Prior art infrared ray detection devices are manufactured by using:
Compound semiconductors such as InSb, Hg.sub.x Cd.sub.1-x Te (0&lt;x&lt;1), Pb.sub.x Sn.sub.1-x Te (0&lt;x&lt;1), etc.; or
an element semiconductor such as Si forming a Schottky barrier at a contact area with a thin metal layer; or
an element semiconductor such as Si, Ge, etc. which has been doped with an impurity such as Zn, Cu, etc.
When a two-dimensional infrared ray imaging device is constructed by using such a prior art infrared ray detection device, it is very difficult to obtain a two-dimensional infrared ray imaging device which can detect infrared rays of a wavelength longer than several .mu.m.
When compound semiconductors are used, for example, since the crystal growth technique for the compound semiconductors is not sufficiently well developed, it is difficult to manufacture a high quality crystal which assures a high electron mobility in the solid state thereof so as to make electronic scanning possible.
Further, in a two-dimensional infrared ray imaging device constructed by using the infrared ray detection device which uses Si to form a Schottky barrier, the cutoff wavelength is approximately 4 .mu.m at most even when using a combination of a Pt silicide and a p-type Si which allows a longest wavelength, so that, so far as a Schottky barrier type infrared ray detection device is concerned, it is impossible to obtain a device of any longer wavelength.
Further, in a device which uses the impurity doped Si since there is a limitation on the amount of impurity doping, it is difficult to manufacture a device having an optional cutoff frequency. Besides, such a device has a low infrared absorption factor and hence low sensitivity.
The present invention has been made to overcome the above-mentioned disadvantages of the prior infrared imaging devices.